The present disclosure relates to a power inductor, and more particularly, to a power inductor having a superior inductance characteristic and improved insulation characteristic and thermal stability.
Power inductors are typically provided to power circuits such as DC-DC converters in portable devices. Such power inductors are being widely used instead of typical wire wound-type choke coils as power circuits are operated at higher frequencies and miniaturized. Also, power inductors are being developed in a trend toward being miniaturized and having high current and low resistance, as portable devices become miniaturized and multifunctional.
A power inductor may be manufactured in a laminate form in which ceramic sheets including multiple ferrites or dielectrics with a small dielectric constant are laminated. Here, metal patterns are formed in coil patterns shapes on the ceramic sheets. The coil patterns formed on each of the ceramic sheets are connected by conductive vias formed on each ceramic sheet, and may define an overlapping structure along a vertical direction in which the sheets are laminated. In general, a body constituting such a power inductor has been conventionally manufactured by using a ferrite material including a quaternary system of nickel (Ni)-zinc (Zn)-copper (Cu)-iron (Fe).
However, the ferrite material has a saturation magnetization value lower than that of a metal material, so that high-current characteristics required by modern portable devices may not be realized. Accordingly, a body constituting a power inductor is manufactured by using metal powders, so that saturation magnetization value may be relatively increased in comparison with the case in which the body is manufactured of ferrite materials. However, when the body is manufactured by using metal, a problem of an increase in material loss may occur because loss of eddy current and hysteresis at a high frequency is increased. To reduce such material loss, a structure in which metal powders are insulated therebetween by a polymer is used.
However, the power inductor which has a body manufactured by using metal powders and polymers has a problem in that inductance decreases as temperatures rises. That is, the temperature of a power inductor rises due to the heat generated from a portable device to which the power inductor is applied. Accordingly, a problem in which inductance decreases as the metal powders constituting the body of the power inductor are heated may occur.
Also, in the power inductor, a coil pattern may contact metal powders inside the body. To prevent this, the coil pattern and the body should be insulated from each other.